Dyeing of textile materials in an aqueous bath with water-insoluble dyes, e.g. disperse, vat, naphthol, sulfur and pigment dyes, is widely practiced. However, the tendency of such dyes to agglomerate interferes with their penetration of textile fiber surfaces, causing problems in dyeing characteristics, e.g. dyeing uniformity and waterfastness. Improvements in such dyeing characteristics are of constant interest and importance in the textile industry. In dyeing of polyester fiber, swelling agents are commonly used to expand the fibers for better dye penetration, but environmental objections have been raised concerning certain of such swelling agents. Diminishment or elimination of their use may become advisable, and an alternate technique for improving the dyeability of polyester fiber is therefore gaining in commercial significance.
Accordingly, it is an object of this invention to provide a process for dyeing of textile materials with water-insoluble dyes in an aqueous bath whereby improved dyeing characteristics, and particularly improved dyeing uniformity and/or waterfastness, are achieved. Another object is to provide such a process which eliminates or at least diminishes the need for use of polyester fiber swelling agents. Another object is a method for the preparation of dye compositions which provide such advantages. Still another object is textile materials having superior dye uniformity as a result of such improved dyeing. These and other objects of the invention will be more fully apparent from the following disclosure in which all percentages and parts are by weight except where otherwise noted, and all temperatures are in degrees Centigrade.